I'll start by saying that our dog and our two cats are actually very responsive to training. One cat is older and just likes to sit and watch the chickens - he's a champion birder when it comes to wild small birds but the chickens will soon be bigger than he is, and I doubt he'll try anything with them. I think he's prudent when it comes to his prey. He won't even attack our rabbit, because though she is a dwarf, she kicks him hard enough. It's the other cat, who has already scratched one of them, that I worry about. As long as he sees me around he won't try anything, because I already scared the crap out of him once by running and screaming at him. It made an impression. Anyway, our coop is strong enough to keep him out so long as it's closed properly. It's the dog I'm really worried about. He weighs 100 lbs (a Bernese-Shepherd cross), and could charge right into the coop if he had sufficient determination. He probably won't be motivated enough, because he's shy of loud noises (abused as a puppy), but he has taken a bit too much interest in the coop so far. He's a funny dog. As long as things don't run he won't chase them, which the cats have figured out, but when he does get the cats he likes to sit and chew on them and drool all over them. But I digress. I'm wondering what you all might have found useful in deterring your pet dogs from being too interested in your chickens.